Method of separating sulphur dioxide and the like from liquid hydrocarbons



P. JODECK ARATING May 23, 1933.

METHOD OF SEP SULPHUR DIOXIDE AND THE LIKE FROM LIQUID HYDROCARBONS Filed Jan. 1929 2 Sheets-Sheet l Wiliam V y l l l Y n l l l I A I I I v l.

f 3 y 2 J @w il n L J o w 4 y f AI y d T @a Z P. JODECK METHOD 0F SEPARATING SULPHUR DIOXIDE AND THE LIKE FROM LIQUID HYDROCARBONS v 2 Sheets-Sheet Z2y May 23, 1933.

Filed Jan. 1 7, 1929 ZSnnentor W I Gimme;

Patented May 23," `1933 UNITED STATES PATENT oEFlcE PAUL J'ODECK, 0F EEB-LIN, GEHANY, 4ASSIGNOB. TO EDELEANU GESELLSCHAFT H. BEBCHBANTXTER HAFTUNG, OF BERLIN, GERMANY xa'rnon or sErmu'rINe summon DIoxIna am) 'run LIKE rn'on LIQUID vmmaocuuuaons application led'laauary 17, 1929Serial No. 383,207, and in Germany october 22, 1928.

This invention finds an important application in the refining of mineral oils, and aims to increase the capacity of the refining plant and decrease the cost of treatment.

5 In the refining of mineral oils by means of the Edeleanu ,process the distillate of mineral oil to be purilied is treated with liquid sulphur dioxide, the unsaturated hydrocarbons contained in the distillate, the quantity of' which varies according to the origin of the material under treatment, bein dissolved by the liquid SO2 and carried own with the latter in the form of an extract.

The recovery of the SO2 used as dissolving means from the extract ina continuous 'op eration prior to this invention has been ,per formed in the following manner:

' The mixture of extract and liquid SO2 containing onel part of liquid extract and about four. to five parts of SO2 is led through vertical tubes connected in ed by means of heating 'ac ets, whereby the l liquid SO2 is evaporate in its greater part. Thetubes open at their top into a container .wherein the' evaporated SO2 is separated from the extract. The SO2 gas is conducted to a water-cooled condenser and liquelied therein, the remaining extract still containing a certain quantity of SO2 (1@ to 1/3 of its volume) in dissolved state. TheA pressure under which the evaporation takes place depends on the temperature of the cooling wa- I ter of 'the condenser and in the most cases amounts to 3 to 4 Atm.V In order to separate.

the remaining SO2 still contained in the extract, the latter has to be led into another evaporator in which this remainder. of SO2 is expelled up to trilling traces both by increased temperature and decreased pressure by means of vacuum pumps. The latter suck off the greatly expanded remainder of SO2 evaporated in the second evaporator and compress the SO2 gas in several pressure stages into the condenser where it is likewise liquefied.

This known process, however, sulers from the drawback that the percentage of SO2 still contained in the remaining extract is comparatively high, so that the dimensions of the vacuum and pressure pumps must be large arallel and heat-V and their power consumption is correspondingly high. Attempts made to reduce the lpercentage of SO2 in the remaining extract ave been ineffective because a more intense heating ofthe extract in the pressure evapop about 30 to 35 degrees C. Only after the SO2 has been-evaporated from the mixture to such an extent that one part of the extract still contains 'about three quarters part of liquid SO2, the temperature of the mixture begins rising notably., In the upper portion of the heating tubes an increased heating and great reduc- 7 tion of the unvaporized remainder of SO2 would be possible but for the fact that the volume of the SO2 already evaporated in the lower o rtion of said tubes lat about 35 degrees is so great that the volume of the other liquid portion disappears in comparlson therewith. This former volume amounts to about the 1000 to the 2000-fo1d .of said latter quantity. Thus the great quantity of of is that in the hitherto used apparatus the extract can be heated only up to about 45 degrecs C. which is insufficient to obtain good se aration. l

ow the object of my invention is to overcome this drawback and to afford a process which enables the highest possible heating ofthe extract in the pressure evaporator to be obtained, in order to expel in this manner all the SO2,`whether in the liquid phase or ab A sorbed vapor or gas excepting a quite trifling percentage. y T his object is obtainedprimarily by sub- )ectlng the liquid to successive or stepwise `increasing -heatng in the pressure evaporator, the SO2 developed being progressively sepa- 100 comparatively cool SO2 vapor or gas prevents 80 SO2 gases ex )elled in this rate the SO2 showing the a rated from the liquid and led o'. This may be performed e. g. by forcing the liquid under a sustained pressure due to the vaporlzation through al battery of heating members connected in series and heated in stages, the S02 gas developed in one stage being separated 'at thepassage from this stage to the next one, these gases thus successively developed then being condensed under the pressure due to vaporization. Manifestly the manner are no longer enable to prevent further heating of the liquid, as they are separated therefrom shortly after having been generated, and the further heating of the liquid takes place ontly after the SO2 vapors developed in the prece ing stage have been withdrawn. In this manner it is possible to gradually heat the liquid up to about 85 degrees C. and to sepaup to a quite trilling percentage, so that the final separation in vacuo may be accomplished by means of comparatively small devices and in an economical and satisfactory manner.

In the accompanying drawings, wherein I have illustrated two embodiments of apparatus intended to carry outmy new process and one embodiment of my process.

Figure 1 shows the first embodiment of a pressure evaporator in longitudinal section, while FigureA 2 is a similar section through the other embodiment.

Fig. 3 is a diagrammatic representation paratus illustrated in Fig. 1 used in connection with a method for recovering the liquid S02 from the unsaturates or extract derived from the liquid S()2 treatment of mineral oils.

As to be seen from Figure 1, the apparatus consists of a plurality of heating members, e. g. tubes 3-8, which are surrounded b heating jackets 9 and on the top open into a common container 10. By means of partitions 11 corresponding in number less one to that of the members 3 8, and rising up to about midway of the container 10, compartments 12-17 are formed in the latter which areopen on the top. Into each of these compartments opens one of the heati 3 8, and a. pipe 18 leads from of each compartment to the next heating member, an outlet pipe 20 containing a regulating valve 19 being connected to the last compartment 17.

he mixture of oil and liquid SO2 is fed to the first heating member 3 from below through a pipe 21, the quantity fed being regulated by a valve 22. Under the action ot the heating means, e. g. waste vapor, fed to the jacket 9, a portion of the SO: is evaporated from the liquid on its way from bottom to top, so that a mixture of SO2 gas and liquid enters the compartment 12. Here the SO2 gas lsseparated from the liquid and llows through membersI d e bottom a dome 23 to the condenser 33, which may be a water or air cooled surface condenser of known type, while the preheated liquid lis fed from below to the next heating member, q This liquid is further 4 through the pipe 18. heated on the way from heating means in jacket 9, so that a, further portion of the S02 is evaporated and separated from the liquid entering the compartment 13 and fed through pipe 18 to the third heating member 5. In the latter, and in the next heating members 6 to 8 this procedure is repeated with the only difference that the liquid fed to the individual heating members, containing less and less SO2, becomes hotter in each stage so that at length a temperature of about 85 degrees C. is reached in the last member 8 and the content of S()2 therein is reduced to about 6 percent of weight, referred to the quantity of oil in the extract.

The oil is led oil' from the last compartment 17 through the pipe 20, its quantity being regulated by valve 19 in such a manner that the liquid level in compartment 17 remains constant, this being ascertained by means of a peep glass 24.

The embodiment illustrated in Fi 2 substantially corresponds to thatof igure bottom to top by the 1, with the difference that the common container 10 is subdivided so as to form a number of individual chambers 25-30 connected by oti'take pipes 31 to a common pipe 32 that leads to the condenser. In this apparatus too, the li uid extract entering from the pipe 2l be ow the first heating member 3 is heated in stages during its passage through the entire apparatus, the S02 gas being led off after each stage through the chambers 25-30. The discharge of extract from the last chamber 30 is controlled likewise by the valve 19 in the outlet pipe 20 to maintain the levcl in y the chamber constant as seen through the peep glass 24. The advantage of this embodiment over that illustrated in Figure 1 substantially resides in the fact that the appara.- tus consists of individual small separate units and can easily be extended by adding such umts.

Referring to Fignl,r` wherein I have shown iagrammatically the application of my method to the separation and recovery of the liquid SO-'J contained in -extract or unsaturates, the untreated mineral oil is passed counter-currently to a descending stream of li uid SO2 in the mixer. 'lhe liquid S 2 dissolves the unsaturated hydrocarbons of the oil and settlesto the bottom as a heavy liquid, known as unfinished extract, which consists of four to tive parts of liquid SOL. to each part of unsaturates. The raiiinate, together with a small amount of liquid S( L is drawn olf at the top of the mixer. The extract and 4liquid SO2 from the bottom of the mixer is pumped into a pressure evaporator constructed, for example, as

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shown in Fig. 1 and already described in connection therewith. The form shown in Fig. 2 may also be used, or any other form constructed to carry out my process for separating and recovering SO2. The evaporator is, operated at a pressure (generally 3 4 atm.)

such that the SO2 gas evolved therefrom may be condensed at cooling water temperatures.

The mixture, enteringby pipe 21, is conducted successively through heating members 9, communicating with the common container or cylinder 10 in which the SO2 gas evolved from the heated liquid is collected. The SO2 gas is conducted from dome 23 to condenser 33.

The extract, containing a. small amount of SO2 which was not driven oif in the pressure evaporator, leaves the latter by pipe 20, controlled by relief valve 19, and enters a vacuum evaporator where further heating takes place. A gas pump sucks Vofi' the SO2 gas whlch is evolved and compresses it to condenser pressure, forcing it into condenser 33 where it is condensed, along with the SO2 gas from the pressure evaporator, by being placed in heat transfer rela-tion with cooling water.

The iinished extract, substantially free from SO2, is drawn from the vacuum evaporator by a pump and made use of as desired.

The liquid SO2 from the condenser is collected in a storage tank, which is maintained at condenser pressure by being in direct communication with the condenser. The liquid S()2 can be drawn off as desired and reused in the mixer. The storage tank is at greater pressure than the mixer and hence the liquid S02 will How from the former to the Vlatter without the use of a pump, the flow being controlled by relief valve 34.-

My invention obviously is not restricted to the particular embodiments thereof herein illust-rated and described.

It is obvious that the process is applicable to liquid mixtures containing other normally gaseous volatile 'solvents in predominating amount such that the volume of gaseousl solvent given of upon heating is so large as to interfere with the further heating of the mixture.

What I claim.l and desire to secure by Letters Patent, iszv 1. A process of evaporating and recovering sulphur dioxide from mixtures of liquid hydrocarbons and SO, with predominatingr percentage of SO, under pressure, consisting inI subjecting the mixture to a stepwise increasing heating under a sustained pressure and separating'and condensing under said pressure the SO, gas evolved by this heating from the liquid in each heating step.

2. The process as specified in claim 1 consisting in passing the mixture through a plurality of externally heated containers connected in series and heated in stages, separating the SO, gas evolved -in each stage upon the liquid passing from one stage the next one, and condensing these gases by cooling under pressure.

3. A process of separating SO2 in the form Ain successive stages under sustained pressure and removing the SO2 gas produced in each stage before subjecting the remaining mix-J ture to treatment in the following stage.

4. The process of separating liquid sulphur dioxide by vaporization from mixtures thereof with liquid hydrocarbons in which the volume of'liquid sulphur dioxide predominates, whichconsists in forcing the mixture under a sustained pressure, due to the vaporization, through a series of alternate heating and se arating containers; allowing the sulphur dioxide gas evolved in each heating container to separate itself from the liquid in the next following separating container, so

lthat the remaining liquid can be raised to a higher temperature in the next following heatin container; and 1i uefying the gas, as evolve by cooling in anot er container while still under the sustained pressure due to the vaporization.

In testimony whereof, I have signed my name to this 4specification.

PAUL JODECK.

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